Wood Destroying Organisms
The following information is from the Certification Training
Manual for the Structural Pesticide Applicator
published around 1975.
Most of the information about pest identification, habits and
damage has not changed. But control practices, especially those involving pesticides,
may have. So always follow the instructions printed on the label of your pesticide
container. You should also study another webpage, "Equipment and Techniques
of Application" included on this website.
WOOD DESTROYING ORGANISMS - COMMON FEATURES OF SPECIFIC PESTS
RECOGNITION, AND CHARACTERISTICS OF PEST PROBLEMS
The most damaging animals that attack wood en structures are the termites. The beetles are the next most important group of insect which attack wood. On the basis of distinctive habits and problem-solving challenges, the beetles rank near the top. There are 2 kinds: those that will re-infest the wood they have emerged from until the wood can no longer be used and must be replaced; and those that emerge from wood after it has been milled (and installed for whatever use it was intended), but for one reason or another cannot attack the same piece of wood again. Third in importance, depending upon geographical location, are the bees, wasps, and ants.
Economic losses from pileworms and certain crustaceans occur in many areas where wood, concrete, and other materials come in contact with sea water. Fungi are also an important source of damage to wooden structures in areas where the climate is normally quite warm and humid. Wood rotting fungal spores are found everywhere and are instantly prepared to germinate as soon as suitable environmental conditions prevail.
The relative importance of a given structural pest may vary from geographical area to area. The following is what California has experienced over a period of time. Taking statistics from quarterly reports in the mid-1960's issued by the Structural Pest Control Board, California Department of Professional and Vocational Standards, there are some distinct trends which are similar to those of many other geographical areas. There was an average of 82,000 reports submitted by licensed pest control operators to the Board for 7, three-month periods. Subterranean termites were found in 43% of the inspections, drywoods in 33%, wood rot in 21%, beetles in 2%, and dampwood termites in less than 1 %. In 41 % of the inspections, faulty grade level was present; in 33%, earth-wood contact was discovered; and in 26%, no infestations and no apparent conditions which could lead to an infestation were found.
LISTS AND KEYS OF PESTS ATTACKING WOOD PRODUCTS
The list presented below is a representation of the most economically important structural pests occurring in the Western United States and Hawaii. The animal list is prepared phylogenetically (i.e., with the most advanced and complex organisms presented last and with the most closely related adjacent to each other).
Mollusca (oysters, clams, mussels, etc.)
- Rock Oyster - Pholadidea penita (Conrad)
- Giant pileworms - Bankia sectacia (Tyron)
- Pileworms (Teredo navalis L., T. diegensis (Bartsch).
- Dampwood termite - Zootermopsis angusticollia (Hagen)
- Nevada dampwood termite - Z. nevadensis (Hagen)
- Drywood termite -Incisitermes minor (Hagen)
- Desert drywood termite – Marginitermes hubbardi (Banks)
- Western subterranean termite - Reticulitermes hesperus (Banks)
- Eastern subterranean termite - R. flavipes (Kollar)
- Black-legged termite - R. tibialis (Banks)
- Western - deathwatch beetle - Trypopitys punctatus (Lee.)
- Softwood powder-post - Hadrobregmus dibbicollis (Lee.)
- Furniture beetle - Anobium punctatum (De Geer)
- Deathwatch beetle - Xestobium rufovillosum (De Geer)
- Lead cableborer - Scobicia declivis (Lee.)
- Blackpolycaon - Polycaon stouti (Lee.)
- Oldworld lyctus beetle - Lyctus brunneus (Stephens)
- European lyctus beetle - L. linearis (Goez)
- Southern lyctus beetle - L. planicollis(Lec.)
- Western lyctus beetle - L. cavicollis (Lee.)
- Giant carpenter ant - Camponotuslevi gatus (Smith)
- A carpenter ant - C. herculeanus, var. modoc L.
- Masculate carpenter and subspecies - C. masulatus (Mayr.)
- Amber carpenter ant - C. maccooki (Forel)
Xylocopidae (Family Apidae by some authors)
- California carpenter bee - Xylocopa californica (Cres.)
- Mountain carpenter bee - X. tabaniformis (Smith)
- Valley carpenter bee - X. brasilianorum (Patton)
Termites are relatively primitive insects being most closely related to the cockroaches. They belong to the order Isoptera. This word means equal wings and refers to the fact that the front and hind wings of alates are of equal size and shape (Iso = equal, ptera = wings).
Entomologists have described about 2,200 species of termites for the entire world. However, when compared to the nearly 300,000 species of beetles described for the world, Isoptera is a small, but still important order. Of the species that have been described, only 70 species infest buildings and require control (Ebeling, 1968). There are 13 species of termites in the contiguous United States that require man's attention to a greater or lesser extent. The 2 most serious species of termites in Hawaii are the Formosan subterranean termite, Coptotermes formosanus and the West Indian drywood termite, Cryptoterres brevis.
Termites occur in virtually every state of the United States and parts of Canada. Alaska is the only state to completely escape thus far. They cause varying degrees of trouble, depending upon the geographical location. The presence or abundance of termites in an area is controlled by their environmental requirements such as temperature, humidity, atmosphere, soil moisture, and soil type. The maps (Fig. 1, 2) illustrate the known distribution of 4 important species of termites in the contiguous United States.
Termites have 3 basic castes; reproductive, workers, and soldiers. There are several kinds of reproductives, 2 kinds of workers, and 2 types of soldiers. In some species, certain castes are missing, in others, all castes are present. The individuals in each caste can be either male or female, but only the reproductives will serve to maintain the colony population. The primary reproductives (or alate, because of the presence of wings), a king and a queen, will remain together throughout their lives. It is necessary for the king and queen to periodically mate to maintain the desired frequency of fertilized eggs. There are secondary (supplementary) reproductives that begin to appear in the colony once it has been established by the primary pair to aid in egg laying. Finally, in some species, there is a third type called tertiary reproductives. These also function to aid in maintaining colony strength.
Most of the work in the colony is done by the worker caste (if one is present) which are sterile adults. Whether there is a worker caste or not, nymphs (future reproductives mostly) help with the tasks of the colony. At one time, soldiers were very effective in warding off the natural enemies of the colony. Today, the heads and mandibles of the soldiers (some species) are large and cumbersome and difficult to swing into action. Soldiers are also sterile adults. In some species there is a second type of soldier, called the nasutus. These individuals wage a chemical warfare against intruders by squirting a sticky fluid from a tube located on the front of the head.
SWARMING AND MATING
Most social insects swarm. This is one means by which certain social invertebrates perpetuate the species. A well-established colony of termites may develop hundreds to thousands of winged kings and queens (primary reproductives), depending on the species. This usually occurs during the time of year best suited to the needs of the termite. For example, if subs (an industry abbreviation for subterranean termites) were to swarm during the month of August in the desert, they would soon perish. Subs prefer warmth and there must be enough water present so that they won't dry out. Therefore, on the first warm day following the first fall rains, subs emerge from their swarm tubes in great numbers.In Hawaii the swarming period extends from May to July with occasionally swarms as early as March, as late as November.
The act of swarming is dangerous. Winged mites tend to be clumsy fliers and are easy prey for hungry birds and predaceous insects. On an average less than 3% of the swarming termites survive. The wind has a strong influence upon the direction and distance traveled by the new kings and queens. Once emerged from the nest the primary reproductives eventually strike the ground out of exhaustion or by accident, they break off their wings along a basal suture, and tandem pairing commences. The queen seeks a suitable location to start another colony. While she is doing this, a king or several kings line up and follow behind her. Frequently, when she turns too abruptly, her followers get lost. Sometimes, males follow males. Before mating takes place a first chamber is built. (Weesner, 1965).
Dampwood or subterranean queens usually locate their beginning nests in a place in the soil, frequently near buried wood. Drywoods prefer a crack in almost any kind of wood. Once mating has occurred (hours to one week or more after swarming), the queen produces eggs of the desired caste.
DEVELOPING THE TERMITARIUM
House building begins immediately. The first year very few offspring are developed in relation to the potential size of the colony. By the end of the second year, many hundreds of individuals will be present. By the end of the third year there may be many thousands. Typically, by the end of the fourth year, most species will have developed large enough colonies to produce visible winged forms of other obvious signs of their presence.
The royal pair care for the first individuals hatched from the first 10 or 15 (or more) eggs. Once the first brood is well developed, more eggs are laid, and this is continued until all castes are present. Workers or nymphs do the chores of extending the colony, feeding the queen and grooming the eggs, themselves, and younger nymphs.
These primitive insects are cryptic in habit. This means living in seclusion, but not necessarily in darkness. This seclusion provides an air controlled termitarium or "carton" in which the termites have limited control of their environment. Man furnishes the heat energy in structures. In the forest and elsewhere in nature, termites go further into the soil as the atmospheric temperature diminishes. Subterranean termites also go further into the soil as the soil moisture diminishes. Under such conditions, drywood and dampwood termites reduce metabolism, develop fewer young, decrease in size, and finally succumb if drying conditions become too severe. For that matter, most termites and other insects fail to attack wood which contains less than 11 to 13% moisture by weight (Chamberlain, 1949).
FOOD, DIGESTION AND GROOMING
Wood is made up of 3 dominant ingredients: cellulose, lignocellulose, and lignin. All plants have varying amounts or proportions of each of these organic substances. The more cellulose in a plant or plant product, the more attractive it is to a termite. Some woods produce toxins or other substances which confer variable susceptibility to termite attack. There are woods from various parts of the world that are quite immune to termite attack (Chamberlain, 1949). However, they are not in abundant supply. Wood products like paper are favorite foods since they are nearly pure wood pulp and cotton fiber. The lignin, a substance avoided by these pests, is removed during the paper manufacturing process.
Cellulose is digested by a large number of flagellated protozoans that live symbiotically, or mutualistically in the intestinal tract of termites. Many kinds of microorganisms are used by animals to aid in their digestion. Some species of termites also use species of bacteria in digestion.
The termite is very resourceful and eats the cast skins and feces of other individuals. Dead or dying colony members are quickly consumed. It is thought that much of this is caused by the fact that termites groom each other with their mandibles. There are secretions, fungus spores, wood particles, and other attractive substances on body surfaces. Inadvertently, sometimes a mandible pierces the very thin integument or skin. When this happens, that hapless individual is eaten by those close by. This is one means by which the cellulose digesting protozoa are transferred from the older to younger colony members.
SUBTERRANEAN TERMITES (RHINOTERMITIDAE)
According to Ebeling (1968), subterraneans are by far the most important pests of buildings throughout the world and the principal effort in prevention and control is directed against these insects. From a standpoint of prevention and control, the chief characteristic of subs is that they ordinarily maintain contact with moist soil. They may reach dry wood above ground through "shelter tubes" ("galleries," "runways") which are constructed from particles of earth or sand (or minute bits of wood, coated with a gluey substance from their mouths and gullets). These termites also cover exposed areas of wood upon which they are feeding with a layer of similar material. After returning to their galleries and nests by means of these tubes, the termites can replenish their body moisture. Breaking contact between wood of the infested building and the soil is a principal method of combating these pests.
In the Rhinotennitidae, 3 species are of considerable importance in the Southwestern United States and Hawaii. These are Reticulitermes hesperus (Fig. 3) in the west, R. flavipes (Fig. 4) in the east (but reported as far west as Texas, New Mexico, and Arizona), and Coptotermes formosanus (Fig. 5), primarily in Hawaii (but also found in several southern states). In California the principal species of subterranean termite is R. hesperus. Winged reproductives (alates) are dark brown to brownish-black and have brownish gray wings. Including the wings, they are about 3/8-inch in length and the body, not including wings, is about 3/ I 6-inch long. Another species of Reticulitermes, R. tibialis, may be found in some inland areas of California, such as the San Joaquin and Sacramento Valleys and certain high deserts. Weesner (1965) states that the reproductives of R. tibialis may be distinguished by their pale almost whitish wings with brownish veins in the fore area, in contrast to the dark wings of R. hesperus. The most reliable distinction between R. hesperus and R. tibialis is the short, broad, dark-colored head of the soldier of the latter compared with the pale, long, narrow head of the soldier of the former. When the 2 species overlap in distribution, R. hesperus prefers cool, shady, moist places while R. tibialis requires open, sunny, drier locations. The 2 species are equally able to damage wood structures.
The flight of the winged reproductives of R. hespents in California occurs between10 a.m. to 3 p.m. on the first sunny day following the first rain of autumn. The colony founding pair (king and queen) may dig some distance to find wood, or may crawl under or into the crevices of a piece of wood on the ground. An irregular cell is constructed in the wood, usually less than 1/8 inch wide and 1 inch long, in which the eggs are laid. There arc usually less than 10 eggs in the first clutch, and from 30 to 90 days are required for hatching. The young nymphs obtain food from the mouth or anus of the parents or workers and in a week also feed on the abundant brown fecal plaster in the nest. In the second instar, the nymph contains the intestinal protozoa which enables it to digest cellulose. For the first 2 years most of the termites reach only the fifth instar and are relatively small. Only a colony large enough to supply enough food and a large amount of fraternal feeding will produce the large, wellmatured workers and reproductive nymphs of the sixth instar; from 2 to 4 months later the reproductives may attain the seventh instar. Workers not falling victim to cannibalism may live 3 to 5 years, and queens probably live much longer.
Supplementary reproductives are required for rapid increase in numbers of termites in a colony. When groups of workers and nymphs are separated from the mother colony, they form a new colony in 6 to 8 weeks, with supplementary queens developed from some of the short-winged nymphs found in every large colony. A supplementary queen can produce more eggs (60 to 80) in a day at the height of egg-laying, than the primary queen does in the first 2 years of the colony's development.
Termites continually groom each other obtaining desired secretions of exudates containing ectohormones. The ectohormones are believed to inhibit the formation of additional members cannot penetrate of the sex (or caste) from which they are obtained. This serves as a regulatory mechanism to prevent a disproportionate ratio of males, females, and soldiers in a colony.
Species of Coptotermes species have an even greater capacity for destruction than Reticulitermes. The Formosan subterranean termite, C. formosanus, a very destructive species in Hawaii, was recently reported from Houston, Texas, and the known infestations were apparently exterminated. The following year it was again found in Houston, Galveston, and in several areas in Louisiana and appeared to have become firmly established in the United States (Fig. 2). On May 6 and again on June 28, 1966, C. formosanus was intercepted in packing material in marine cargo in Lathrop, California. On June 14, 1967, 2 Formosan termites were found in a residence in Charleston, South Carolina. Because all infestations had been in harbor cities, it is almost certain that these termites came aboard ship to the U.S. Many believe that C. formosanus will eventually have the same range of distribution in latitude in the U.S. as it has in other areas of the world.
The most obvious characteristics distinguishing C. formosanus from the native Reticulitermes is its larger size, pale yellow body color, oval shape of the head of the soldier in comparison with the oblong and rectangular head of the Reticulitermes soldier, and the hairy wings (Fig. 6).
Formosan termites make nests of a hardened paper-like material called carton in wood in or on the ground, in hollows they have excavated from tree stumps or posts, or in hollow spaces in the walls, floors; or attics of buildings. Runways from nest to wood have been found as deep as 10 feet underground and from 150 to 300, or more, feet long. Beside the primary nest, the older, larger colonies of the Formosan termite frequently build secondary nests close to food sources; these nests contain mainly workers, soldiers, and older nymphs. Like the native subterranean termites of the U.S., termite builds earthen shelter tubes over objects it cannot penetrate.
C. formosanus flights usually begin before sundown in May or June and end before 9 p.m. Warm, sultry evenings are favorable for extensive flights. These insects are strongly attracted to lights. In contrast to C. formosanus, other subterranean termites such as those that fly during the day, as might be inferred from their black bodies.
Alates of C. formosanus drop to the ground beneath lights and remove their wings. Pairs in tandem can be seen scurrying around searching for suitable amounts of food and adequate quantities of moisture. The alates enclose a small chamber and mate. The first clutch of eggs which is laid soon after mating contain seven to fifteen eggs. The eggs hatch in 45 to 60 days depending on temperature. Eventually, after five or more years a major colony containing up to eight million termites is formed.
DRYWOOD AND DAMPWOOD TERMITES (KALOTERMITIDAE and HODOTERMITIDAE)
These destructive pests are placed in the families Kalotermitidae and Hodotermitidae which includes about 16 species in the United States. There are 2 genera in these families of concern to the pest control operator. One of these is the western drywood termite, Incisitermes minor and the other is the Pacific dampwood termite, Zootermopsis angusticollis.
In Hawaii the Kalotermitidae is represented by the West Indian drywood termite, Cryptotermes brevis; the lowland tree termite, Incisitermes immigrans; and the forest tree termite, Neotermes connexus. Of these only the West Indian drywood termite is of major concern although the lowland tree termite has been found attacking homes in a couple of instances. The dampwood termite does not occur in Hawaii.
These families have no worker caste; the nymphs, as they continue to molt to adulthood, do the tasks of the workers. Ground contact is not necessary for the drywood. Infestations may be found in structural timber and woodwork in buildings including furniture, telephone poles, wooden derricks; bridges, various dimensions of lumber found neatly stacked in lumber yards, paper, cloth, woodpulp or fiber insulation boards and in other products containing cellulose.
The western drywood termite tends to cut across wood grain, destroying both the soft spring wood and the harder summer growth (Fig. 18' of key). Subs strongly follow the grain of the wood, usually foraging only the soft spring wood (Fig. 18 of key). Contrary to subs (which develop liquid feces), the drywood termite develop pellets of specific size and markings (Fig. 5 of key). These pellets are eliminated from the galleries through "kick holes." Pellets tend to accumulate on surfaces located below the kick holes and are the best evidence of drywood termite presence. The more concentrated the pile, the closer the kick hole is located to the surface below. If the pellets fall several feet, they are spread out and form indistinct piles. In comparison to other termites, drywood colonies are rather small (a few thousand individuals). However, as swarming takes place within a structure, many new colonies will be formed until a dwelling generally becomes infested. Unless the entire structure is fumigated, it is usually impossible to delimit the infestation without removing plaster from the inside, or siding from the outside. The latter procedure is rarely used today.
I. minor swarms during the daylight hours, usually during the months of September and October is Southern California. Essig (1958) states that this species will swarm during the month of July in Arizona. They fly into attics or substructural areas of poorly vented houses. A favorite place for entry is in the crack created by drying plaster as it pulls away from window and door frames. It is necessary for most termites to be able to get a purchase (mechanical aid) on the wood that it intends invading. Normally, termites will not just land on wood and tunnel. However, if they can crawl down into cracks and crevices, there is not a problem with excavation.
Swarming of C. brevis can occur at any time of the year-in Hawaii, but most frequently occurs in the evening during spring and summer. Mating takes place after a chamber is formed. The eggs take about 60 days to hatch and only about ten eggs are laid the first year. No soldier or alates were produced (McMahan,1962). Colonies contain only a couple of hundred individuals although galleries from several colonies may coalesce in a severely infested piece.
Dampwood termites are of minor importance from a world standpoint, but they form a distinct habitat group. Dampwood termites locate their colonies in damp, often decaying wood; but once established, they can extend their activities into sound and even relatively dry wood (Fig. 7).
They enter wood directly at the time of swarming and always confine their work to wood. They are occasionally responsible for serious damage to wooden structures, usually in conjunction with fungus attack, since the moisture requirements of both are similar.
Flights (swarming) of the dampwood termites are usually crepuscular (dusk). Some flights occur throughout the entire year; however, peak annual swarming takes place in late summer and fall. In Northern California and the Pacific Northwest, Zootermopsis augusticollis, the Pacific dampwood termite, and Z. nevadensis occupy a similar range; the latter predominating in cooler, drier, higher areas. Z. angusticollis extends southward along coastal California and eastward along the damp stream beds of foothill canyons and on into the mountains:
The winged reproductive Z. angusticollis may be an inch or more long, including the wings; the wings are from 7/8 to an inch long. The body is light cinnamon-brown; the wings are light to dark brown, heavily veined, and leathery in appearance. The soldiers (Fig. 8) are 3/8 to 3/4 inch (or more) long, depending upon the instar in which they assumed their typical soldier characteristics. This varies with the age of the colony, which is somewhat true of many species of termites (Fig. 9). As with other members of this family, there is no worker class. The nymphs and dealated reproductives are about 1/2 inch long.
WOOD BORING BEETLES
Beetles belong to the largest order of insects in the world. The order is called Coleoptera, which means leather wing. This refers to the front wings which are chitinous (hard substance in the insect skeleton) and cover the abdomen (Fig. 10). Beetles have complete metamorphosis. The young are typically the damaging stage. Pupation usually occurs in the wood in which the larvae feed This so-called resting stage lasts, for most wood infesting beetles, about 10 days to 2 weeks. It is not actually a resting stage, but nature's way of changing a worm-like grub into a completely different appearing adult beetle with wings.
BEETLES THAT RE-INFEST
There are 3 important families of beetles that not only continue to re-infest, but frequently reduce the wood products to a powder if left undisturbed. They are called powderpost, or false powderpost beetles. They belong to the families Anobiidae, deathwatch beetles; Bostrichidae, branch and twig borers, and Lyctidae, true powderpost beetles.
The common name applied to these beetles is the result of an old superstition. Years ago, when homes were built mostly of wood, they would become infested with anobiid beetles. At mating time, the sex call of the beetles consists of a tapping noise made by striking a part of the body against wood. In some instances, this tapping was taken as a sign which foretold of the death of a member of the household. Naturally, as one would sit up with those near death in the late of night, there was enough silence within the house to actually hear a number of these wood boring beetles calling their mates.
The anobiids are small (1/16 inch to 3/8 inch) and when viewed from above, the head is entirely hidden under the hood-like thorax (Fig. 11). The body is quite cylindrical. The 11-segmented antennae are inserted at the sides near the eyes with the 3 terminal segments somewhat enlarged forming a club. The larvae are humpbacked in appearance due to the enlarged thoracic segments. As indicated briefly in the key, the pellets are left in galleries in isolated clumps of different sizes (Fig. 7 of key) with galleries traveling both with and against the grain.
The western deathwatch beetle, Trypopitus punctatus, has been found destroying oak flooring, hardwood finish, and furniture. The softwood powderpost beetle, Hadrobregmus gibbicollis (Fig. 11) mines maple and wild prune in nature. However, the damage they cause is mainly from their attack on douglas fir. They have been found mining in timbers of bridges and under buildings. Such materials may be so completely mined as to require complete replacing. Although the soft parts of the timber maybe mined first, eventually, the entire interior will be reduced to powder. This pest is most frequently associated with moist wood being attacked by wood rotting fungi.
BRANCH AND TWIG BORERS
These insects are also called "false powderpost beetles." There are 2 species in this family (Bostrichidae) that cause structural problems, the lead cable borer, Scobicia declivis and the black polycaon, Polycaon stouti. The first species is quite typical in shape and appearance (Fig. 12) to other members of the family. The lead cable borer adults infrequently bore into lead sheathing of telephone cables leaving holes up to 1/8 inch in diameter. Rain and other moisture sources enter into the cables through these holes and may cause telephone service disruption through short circuits. The species normally attacks maple, oak, and other hardwoods in nature. The head is lodged in the spherical pronotum like a ball and socket joint, making it impossible to see the head from above. The last 3 segments of the antennae are distinctly enlarged. Adults are dark brown to black and about 1/4 inch long. This pest may easily be confused with adults of the bark beetle.
As is typical of most members of this family, the eggs of the lead cable borer are deposited in old larval galleries or any crack and crevices in wood into which the adult female is able to crawl. The larvae primarily mine the wood with the grain. An emerging adult will turn at right angles from the larval mine and work its way out of the wood. The larval galleries are tightly packed with frass which is left as the young work through the wood.
The black polycaon adult does not have the typical family shape (Fig. 13). The life cycle is similar to that of the lead cable borer. The adult is a black, stout beetle, 3/4inch long. The larvae tunnel in dead oak, maple, alder, eucalyptus, sycamore and other western hardwoods in Oregon, California and Arizona. The species has caused considerable damage to furniture and hardwood veneer plywoods. It also bores in rustic work, logs of cabins, and hardwood lumber when stored for a considerable time.
TRUE POWDERPOST BEETLES
The members of this family are from 1/8 inch to 5/16 inch long, somewhat flattened and from light brown to black in color (Fig. 14). The head is prominent and not covered by the pronotum. The antennae are 11-segmented and the club is rounded consisting of but 2 segments. The head being visible from above will separate members of this family from most other so-called powderpost beetles.
In nature, these beetles breed in old,well-cured wood, but are frequent household pests working in furniture, flooring, tool handles, and other hardwood products. There is no way to visually determine the presence of an infestation until the first adults emerge through the wood surface creating pin holes.
The females lay eggs in the pores of the end cuts of the wood. These pests do not attack soft wood (e.g., pine, douglas fir). This may be associated with the lack of suitable pores in these wood and hence egg laying sites (Fig. 15). Solid and veneer ash is a favored wood for kitchens and other areas of southwestern homes. This wood is also favored food for several species of lyctid beetles. The starch content of the wood appears to be a primary basis for selection.
The southern and western lyctid beetles are the most common and troublesome species. These destructive beetles require approximately one year to complete a life cycle from egg to adult. In an in-house infestation, eggs may be laid during any month of the year. In nature, eggs are laid normally during the spring.
BEETLES THAT CANNOT RE-INFEST
There are a large array of beetle families that infest wood in nature. They attack forest trees in all stages of vigor, but tend to concentrate on weakened trees. The larvae and occasionally other stages of these families may end up in timber products and find their way into structures of one kind or another. Most of these families are unimportant, but there are at least 3 which are of continuous concern to pest control operators. Some of the most perplexing problems are created by the beetles that lay eggs within bark crevices on trees that are freshly cut. Their offspring can complete their life cycle in uncured lumber and frequently are "built into homes" and eventually emerge as adults from beam ceilings and subflooring through polished hardwood flooring, other floor coverings and wall plastering. Since these adults cannot find a suitable place to lay eggs within a man-made structure, they perish. These beetles which are commonly called flatheaded borers, roundheaded borers, and bark and timber beetles must have bark, the cambium layer, or living sour sap xylem (wood) for the placement of eggs. None of these conditions normally occur within man-made wooden structures.
METALLIC WOOD BORERS
These are brightly colored, beautiful beetles particularly when found in nature. As larvae, they are called flatheaded wood borers (Fig. 16). The head of the larvae is much wider than it is thick. The adult female must have bark upon which to lay eggs, which are wedged into crevices or under bark scales. Eggs are deposited in the spring and summer. The most damaging species of flatheaded borers are those with long life cycles, and the larvae may remain for years before becoming an adult. Often, the cycle is of such a nature that adults commence emerging not long after structural timber (2x 4's, 4 x 4's or larger stock) is used. The home buyer suddenly realizes that his home is infested with beetles. Most Buprestidae adults are large, from 1/2 inch to 2 inches in length. The large size makes it difficult to miss these beetles when they begin emerging from walls.
Their name comes from the fact that the antennae of these-beetles are usually as long or longer than the entire body (Fig. 17). The larvae are called roundheaded borers. For all practical purposes, the habits ofthis family are very similar to the flatheaded borers. The adult female must have bark upon which to deposit eggs. Burned, injured, or downed trees and saw logs are most attractive. Man frequently finds it convenient and inexpensive to harvest timber which has been injured in some way. As a result, these harvests result in lumber which may be infested by some kind of wood boring beetle. Some members of this family, the longhorned beetles, are among the largest insects in the world.
BARK AND TIMBER BEETLES
The bark beetles feed in the larval stage on the cambium layer (the layer of cells growing in between the wood and the bark) of woody trees. The adult timber beetles (Fig. 18) penetrate the sapwood when the tree is in a sour sap condition; (i.e., the sugar and starch in the sap has commenced to ferment). Ambrosia fungal spores are brought in with the adults and grow on the fermenting sap. The larvae are fed on the spores produced by the fungus. The fungus frequently stains and downgrades the quality of the wood. Both hardwoods (oak, black walnut, pecan, ash, birch) and softwoods (douglas fir, pine, spruce, cedar) are subject to attack.
As with the 2 preceding families, attack must commence in the forest. If adults emerge in homes of other structures, they are attracted to windows or other areas of light. Large numbers of these beetles may emerge in a home when an individual cuts down a tree, chops it into cord wood and leaves it exposed to nature just long enough to attract bark or timber beetles.Then the wood is brought into the wood storage area, usually in a basement. Once the eggs hatch and the larvae feed to maturity and pupate, thousands of adults will soon emerge. This frightens the home owner and sometimes the pest control operator. Remember, bark beetles will not re-infest.
BEES, WASPS, AND ANTS AS TIMBER PRODUCTS PESTS
Carpenter ants are frequently found emerging from wooden structures. In the eastern United States, these pests work wood much like drywood termites. On the West Coast, carpenter ants ordinarily do not cause economic damage to wooden structures but typically occupy nests abandoned by other organisms. Old drywood termite nests are frequently occupied by a number of species of carpenter ants. Carpenter ants are meticulous; they clear everything from the galleries. Thin and unwanted partitions are removed, but the gallery is not enlarged to any great extent (Fig. 18' of key). Their cleaning activities create distinct piles of different kinds of pellets, chips of wood, and other debris. Such piles are placed in locations near the nest and are diagnostic of carpenter ant infestations.
The workers are found at night roaming around various areas searching for sweets of one kind or another. These pests do not eat wood. The workers are large, long legged and black to brown in coloration (or some combination of the 2 colors) (Fig. 19). Several sized worker adults may occur in one colony. Usually, one must find the piles of frass in order to locate the small doorways through which they travel. If there are too many ants and all their locations cannot be found, fumigation might become necessary.
Carpenter bees prefer soft woods (Fig. 20), but occasionally go to harder woods as eucalyptus. There are 3 species in the western United States, none of which cause serious damage, except to isolated structures. Mountain cabins and bridges built with redwood, tend to be most subject to attack. Piles of pencil shaving-like frass are frequently found near gallery entrances. Their attacks are periodical, and environmental conditions strongly control their response to certain kinds of wood. For example, following flood years in many of the canyons containing native white or creek alder, there becomes available a large quantity of the mountain carpenter bee's favorite colony-building wood. Less desirable wood, found in structures, would tend to be ignored under these conditions.
Marine borers have been a source of damage in all parts of the world since man took to sea in boats or built structures which came in contact with salt water. In favored localities these wood pests occur in countless numbers and work with a rapidity seldom met, even among insects.
Marine borers belong to 2 distinct classes of animals, the Mollusca (bi-valves) and Crustacea (crabs, lobsters). Most of the wood boring mollusks belong to one family known as Teredinidae. This family is composed entirely of burrowing species which typically drill tunnels in wood and line them with a thin layer of shell-like substance. Such tunnels may have a length of 4 feet or more (Fig. 16 of key). Each species excavates a mine which is quite characteristic in size and shell-lined appearance. The borers have long slender bodies, small shells and a pair of plumose or, paddle-shaped pallets near their siphons. Their pallets serve to close or plug the opening at the outer end of their burrows to exclude intruders. The food of these marine animals is plankton; therefore, their work in ships, pilings, and wharfs is for reasons similar to carpenter bees, simply a place in which to live and from which to feed. For example, the giant pileworm will completely destroy untreated pilings in 6 months under favorable conditions.
FUNGI ATTACKING WOOD PRODUCTS
Wood decay is caused by minute plants called fungi. These plants consist of microscopic threads that are only visible to the naked eye when many of them occur together. The fruiting bodies (deadwood conks, mushrooms) of fungi from which their spores are distributed are easy to see. Some fungi merely discolor wood, but decay fungi destroy the fiber. Decayed wood is often dry in the final stages, but not while the decay is taking place since these fungi require considerable moisture (Fig. 2 of key). Therefore, there is no such thing as "dry rot," and decay is a. minor problem in the driest parts of the country.
Sores or “seeds” of decay fungi are always present in the air; they can’t be kept away from wood. But fungi can grow in wood only when it contains more than 20% moisture. Air-dry wood is regularly below this danger point. One should particularly avoid infested lumber that is wet. It is especially dangerous where the lumber is so enclosed that it cannot dry. Wood infested heavily by stain fungi should also be avoided since it often contains decay fungi as well.
SOURCES AND CAUSES OF STRUCTURAL PEST PROBLEMS
Water and Moisture
The control of the presence of excessive water, no matter where it comes from, is of primary importance. Rain, water of condensation, water runoff (particularly where drainage and grade is poor), excessive ornamental plant irrigation, atmospheric moisture and leaky plumbing are a few examples of water sources. If water problem sources are ignored, serious structural damage will invariably result.
Using excessive water to irrigate plants adjacent to dwellings and other structures is a common practice in many of the dry areas of the southwest. In Hawaii, soil water is ever present, providing an optimum and continuous supply of needed water to the Formosan subterranean termites. Deep soaking of shrubs and trees growing near wooden structures gives the subs the moisture they need to commence, and maintain, a large colony. Controlled watering of plants is vital to the minimization of structural pests.
Faulty plumbing is another source of extraneous water which can be very simply controlled. If water is coming from leaking plumbing (a frequent defect) and the source can be located, the leak can be terminated. The 2 most common leak sources are improperly installed shower pans and toilet stools.
Another common source of water is faulty grade of the soil in and around structures. Figure 21 shows grade sloped away from foundation. For example, in one instance around a Southern California home, when it rained, the run-off made its way around the house through the crawl space and hence into the earthenfloored basement. The unusual amount of water in this situation caused several posts supporting the substructural timbers to sink into the mud. It wasn't long before subterranean termites began to appear in abundance. The sinking of the posts (4 x 4’s) was so great that a number of doors on the first floor of the dwelling could not be closed. In this particular case, the poor grade and several structural mistakes cost the home owner considerably for the repair and corrections. When dealing with problems caused by unnecessary water, one must use ingenuity and thoroughness. Many times, terminating the water source completely eliminates the structural pest problems.
Exterior moisture may also be due to a downspout emptying in a spot where drainage is poor, high wet soil in a planter, seepage created by a high angle slope above one side of the house, high exterior grade, vertical cracks in the foundation, low ventbases permitting moisture to flow under the house, cracked away vent-wells, large vertical openings on either side of a chimney set in the foundation and many other similar situations. If a house is located near the coast, moisture from the heavy, wet fogs is sucked in under shingles, keeping the outer eave sheathing damp.
Soil types, textures, depths, and chemistry are all closely related to moisture problems. Obviously, some soils will hold more moisture than others. There are sandy soils that will hold so little water that termites (subs) are unable to survive. For example, where structures are built on old river beds and washes, subterranean termites arc usually absent. However, there may be areas immediately adjacent where natural water courses have bid down thick layers of silty, clay loam where subs abound. In Hawaii, however, sufficient water is available even in sandy soils.
Earth to Wood Contact
If proper soil conditions prevail, any direct contact between earth and wood is an invitation to attack by subterranean termites and fungus decay. Some earth to wood contacts are readily visible and some may be inaccessible.
Around the exterior of a building, we may find any of a number of wooden structures in contact with the ground. These may include wooden ventframe, a fence or gate post attached to the house or to the garage, wood siding, flower boxes, masonry planters, lower steps of wooden stairways, trellis stakes, wooden dividers between concrete or masonry squares in a patio, wooden or stucco-covered archways, carport supporting post, and many others too numerous to mention. If a house has a crawl space some of the many possibilities of earth-to-wood contacts include stakes (either grade or form supports), temporary wood posts left in place under hearths or under heavy appliance installations, angular bracing extending into the soil, , wood and paper boxes used as storage under houses, wood blocks supporting plumbing and or heating ducts, and earth-filled porches and patios where the earth makes contact with some part of the wood framing of the substructure (Fig. 22).
Slab on Grade Construction
Slab on grade construction may also have problems from the subterranean termite attack. When not monolithically poured, shrinkage cracks often occur between porches or patios and the main floor-slab in modern concrete slab construction (Fig 23).
DRYWOOD TERMITE ATTACK
The dead limbs in fruit, nut and ornamental trees are often attacked by drywood termites. When such trees are in close proximity to a structure, they constitute a definite hazard. Drywood termites may build up in these materials and then migrate to structures. When old utility poles are within a 100-foot radius of a structure, they are hazardous especially when not properly treated chemically. Infested fences and temporary type structures (such as storage rooms, play houses, tool sheds) may be sources of infestation by these termites.
The material presented in this section is based on Inspection for Wood Destroying Organisms, Ronald W. Hunt, Sr. 1966.
A good light is essential and most inspectors prefer the five-cell flashlight. Extra batteries and bulbs for the light may often prevent unnecessary delays. A heavy jackknife, an ice pick or a small wood chisel for probing into the wood is also a necessity. A thick piece of spring steel or a hacksaw blade is needed for testing earthfills. A screwdriver, measuring tape and hammer should be included with the equipment. A light, strong 6-foot stepladder is essential. Coveralls, a stocking cap, gloves and sponge-rubber kneepads make up the balance of the essential equipment. Persons subject to dust irritation should also include a small compact respirator.
Some inspectors carry cameras with flash attachments to photograph special conditions. A sizeable clipboard equipped with cross-section paper is handy to sketch a diagram of the structure and make notes of findings. Finally, a whisk broom, some waterless soap and a supply of clean rags are additions to include with the equipment.
Procedure will be divided into 4 parts: the examination of the exterior, the interior, the attic and the substructural area. Before proceeding with the inspection, the inspector should explain his mission to the occupant. A few questions concerning his or her observations regarding insect occurrence, damage, plumbing leaks or other irregularities, may be very helpful.
Walk slowly around the structure pacing off the approximate measurements and draw a rough diagram. By using "engineering" cross-section paper which is laid out on the decimal system, the inspector will find it easier when totaling the lineal feet. Set in the porches, patios, vents, ventwells, columns and pilasters. Also record the moist areas, exterior grade conditions, vertical foundation cracks and exterior earth-to-wood contacts. If the structure is stucco finished, tap the stucco below the top of the foundation with a heavy pocket knife, hammer or some object heavy enough to produce a hollow sound if the basal stucco is loose.
This phase of the inspection is very important whether the structure is on a slab or is a crawl space type. Many of the earlier concrete slab-type houses have an exterior plumbing vent or hatch which should be removed and the inside checked. Many of the older stucco finished structures were decorated with columns, pilaster and arches as well as buttress-walls; these were not always provided with a proper footing and should be checked. If the footing conditions are doubtful, it may be necessary to recommend opening and would thus necessitate an additional inspection with supplemental report. Note shrinkage cracks between the foundation and such attachments as concrete porches, patios vent-wells, masonry or concrete planters, stone facings, and masonry chimneys.
The size and condition of substructural ventilators is a must in the case of F.H.A. inspections or where Uniform Building Code requirements are present. The condition of the crawl-vents is of primary importance if small children or animals are to be kept out of the sub-area. If the vent-frames are of wood, note deterioration or exterior earth-contact. Where shrubbery is dense adjacent to the structure, ventilators may be partially or completely blocked.
Don't forget to look up as well as down! The wood structure in the eave-area may show indications of drywood termite colonization or fungus decay. The excrement pellets of drywood termites are quite often caught in spider webs or a few may be resting on a projecting ledge. In coastal locations check the outer eave-boards, where moisture collects and fungus infection is likely to occur. Watch for clogged "valleys" and eave-troughs. If it is a two-storied structure and suspicious discolorations are in evidence, inspection from an extension ladder is indicated. In two-story apartment buildings, front, rear or side stairways are provided for access to the upper level. If either the stairs or stair landings are enclosed by stucco, be sure to note the presence or absence of access doors and/or ventilation of the enclosed portions. If found to be inaccessible, these enclosed areas may be seriously attacked by either fungus, termites or both. During these exterior observations, make careful notations on your diagram and do not trust your memory as findings in other areas may distract you and earlier observations may be forgotten.
Exterior inspection of houses with concrete slabs is similar to crawl-space houses but there are certain points which should be stressed. The combination of high exterior grade and loose stucco is "dynamite" in slab construction. Planters are more often a hazard and vertical cracks in the main slab may result in both moisture penetration and infestation by subterranean termites. Open and inspect plumbing hatches and electrical meter and fuse-boxes. Normal shrinkage cracks between porches and patios and the main slab should be inspected. Be sure to check concrete attachments installed by the owner. If these are poured without prior stucco removal they may present a serious hazard. Fence and gate posts adjacent to a slab type house are hazardous, especially where the soil is built up in gardening.
Inspection of the Interior
Generally speaking, the condition of plumbing fixtures and plumbed appliances are the most important part of interior inspection. Although the stall shower is most often the prime offender, the inspector should not overlook a built-in tub which may have insufficient wall protection or calking. A leaking dishwasher, washing machine, water heater, garbage disposal and/or the drainage system under sinks and washstands are always suspect.
Leakage of stall showers is a prime source of moisture accumulation. Many operators prefer to test for leakage by bucketing in the water for floor, pan and subdrain testing. Then, after checking conditions in the sub-area beneath the shower they return to the bathroom and open both shower valves. Leaks in valve-packing and wall-tile penetration will seldom be missed if this is done. Don't forget to check the toilet stool for leakage. This latter type of leak has the potential to rot out the entire bathroom floor in crawl-space houses. In homes built close to the ocean or inland salt water bays, the oxidation of iron water pipes is very rapid and leakage in the wall areas is frequent. Wooden window sashes are always subject to moisture deterioration and the attacks of drywood termites. In the interior valleys, the putty dries and cracks, permitting the rain and condensation moisture to accumulate in the glass channel.
Interior inspection of houses on slabs does not vary much from that in crawl-space homes. However, there are a few special points which should be stressed. Plumbing leaks will cause linoleum to loosen, asphalt tile to buckle or produce stains. Plumbing or conduit openings through the slab are points of entry for subterranean termites. These plumbing hatches may reveal fungus damage, subterranean termite activity, earth-contacts due to burrowing animals or leaking pipe joints.
The Attic Area
Indications of drywood termite attack such as wings or frass, may often be found even though no piles of pellets or active colonies are located. The tops of ceiling-joists, the button lath or batttype insulation directly beneath the ridge-board and the area adjacent to or just beneath attic vents are locations one should always check for drywood termite pellets, wings and/or frass. If you note what appears to be a pile of sawdust on the upper plate near the eaves and you find it impossible to get close enough for a good look, moisten your hack saw blade and pick up a sample for accurate identification. Fungus infections due to roof drain stoppage may be in evidence in these areas. The presence of buckets, pans and the like found in an attic generally indicates roof leaks. It is not uncommon to find shelter tubes of subterranean termites in portions of the attic directly above earth-filled porches, hearths and closed in concrete patios. In recent years the presence of wood-boring beetle damage in the attic area has become more noticeable. Some of this damage may have occurred in the forest but the extensive building program of the last few years has allowed less time for lumber curing and active beetle colonies are not uncommon. This is especially true in the case of bark beetles.
While in the attic, it is a good idea to note any evidence of household insects or rodents. In many areas, opossums and even skunks have taken up residence in the attic areas of older, vine-covered, frame houses. Silverfish, cockroaches, hornets, wasps, honey bees and especially birds and bats are frequently found in attics. When you have completed the inspection of the attic, obtain a moist cloth so that you may remove the finger marks from the exposed portion of the attic hatch.
In the event that no way of access into the attic can be found, estimate its accessibility from the exterior and recommend the cutting of a hatch if you are satisfied that sufficient clearance exists. Sometimes excessive bracing, roof additions and blown-in insulation limit the accessibility of the attic area and these facts must be set down in the notes. If the simple removal and replacement of a single brace or the opening of an abandoned roof section is all that is necessary to make the entire attic accessible, do not shirk your responsibility by failing to examine it.
Crawl-space Inspection (Substructural Area)
In the past, the conventional pattern of the sub-area inspection was nearly always made in a narrow path around the under area adjacent to the foundation. An exception would be in the case of large buildings where cross-walls interfered. Although cross-walls are utilized under single story structures, they are always found under bearing partitions in buildings of 2 or more stories. In contemporary homes, many things interfere with the so-called "conventional pattern." These interferences are the relocation of appliances such as automatic washing machines, driers, water heaters and dishwashers and the fact that bathrooms are not always contingent with the foundation as they always were in the past. Leaking water lines and plumbing connections may now occur several feet away from the foundation. Some of the worst offenders are side-opening dishwashers and condensation water in both washing machines and dishwashers where ventilation is defective. This permits a build-up of steam pressure within the appliance. We can no longer be satisfied with the fact that the plumbing along the foundation appears dry. All this points to a wider path of inspection and a route beneath each bath, half bath or relocated water-connected appliance. Having already examined both the exterior and interior, the inspector should have the strategic points well in mind. Most likely these will be the location of earth-filled porches, patios, embedded vent-frames, planters, damp areas, bathrooms and water-connected appliance locations.
The general practice in checking an earth-fill porch is to slip a thin metal probe under the mudsill (sill) to locate either a void or thefill itself (Fig. 24). If the probe penetrates the area beneath a porch cap freely, no "seal" exists, but if it strikes a hard surface back of the mudsill, a question arises as tothe presenceofa contact. In the latter case the earth-fill is either sealed off or some structure has interfered and the seal is questionable. Where a porch-seal is in question, make a diligent search for the presence of shelter tubes of subterranean termites before reaching any conclusion. Experience has shown that a probe may fail to penetrate all but a small sector so don't give up after a few tries ...blade it all! Some inspectors use light colored chalk or crayon to make arrows on the foundation indicating penetration points or evidence of infestation. These are valuable guides when reinspections are made at later dates.
Within reasonable sight-range, most vertical shelter tubes of subterranean termites attached to the foundation (Fig. 25); and free-standing swarmer tubes are readily visible. One must be much more alert to spot horizontal tunnels extended along the mudsill, in subfloorcracks, at the edges of blocking and those extending along floor joists and girders. If possible the latter should be traced to their point of origin. The colony may have originated in an earth-fill, an exterior planter, an embedded exterior ventframe, a vertical foundation crack, some loose stucco, a wooden structure attached to the house or some other earth-to-wood contact.
As previously stated, good visibility cannot be obtained at distances of more than 15 to 18 feet. Therefore, if the structure exceeds 36 feet in width, 1 or 2 extra routes traversing the central portion becomes necessary.
Known locations of drywood termite colonies in the periphery of the attic or at approximate interior locations help the inspector to spot accumulations of excrement pellets in the sub area. Large piles of dropping spill over the mudsill onto the ground and are more easily discovered. Compact piles of drywood termite pellets indicate a source close at hand while scatteredpellets suggest a more distant origin.
Some locations in the sub-area which should be given particular notice are: areas directly beneath floor furnaces, soil pipe openings through foundations, wood forms or stakes left in place by the builder, cellulose debris, tree stumps, plumbing or heating ducts supported on wood blocks, moist areas, vertical foundation cracks and piled up earth. Check carefully under the stall shower which has been previously water-tested. If it is damp or dripping, determine the source of the leak. Probe the subfloor for softness. This goes for stained areas whether dry or wet. Where one inch subfloor is used, it may be necessary to arrange the removal of a section to reach a verdict. Don't overlook the flooring and joists directly beneath the toilet stool. Although everything may look "ship-shape" in the bathroom, the real story will reveal itself directly beneath the stool. Dry dormant fungus decay beneath a toilet indicates that the toiletwasreset without floor-repair. Such a condition is a serious hazard because a new leak will reactivate the fungus development.
One of the primary problems involved in garage inspection is storage. If the inspector cannot reach all the strategic portions of the garage due to storage, make note of this and suggest a supplemental inspection and report when these can be made available. Sometimes garages are partially or completely "finished" on the inside and except for the door and door-jamb, a garage like this may be inaccessible for inspection. In the southwest where both subterranean and drywood termites occur, a proper inspection includes the mudsill, studding, upper plates, rafters and sheating. Flat roofed garagesaresubject to fungus decay adjacent to the drain or down-spout area. The header above the door is a spot that is easily missed, especially when there is an open overhead door. Shrinkage cracks adjacent to the foundation and diagonal cracks passing under the mudsill are definite garage hazards.
Somegarage-owners have built-in colonies of drywood termites with infested shelving, storage rooms, benches and the like. Sometimes infested stored furniture, and firewood may be the source of the garage infestation of drywood termites or wood-boring beetles. Small temporary-type structures built onto the sides or rear ofthegarage may not be properly insulated from the ground. Where the garage is an integral part of the house, it becomes as important as any other portion. If the garage is used as a laundry, check all waterconnected appliances. A locked garage generally means a supplementary inspection and report unless the owner refuses to permit the inspection. In this case, explain the circumstances in your report. High exterior grade conditions and piles of trash or stored lumber adjacent to the outer walls of the garage are definite hazards. The common points of faulty home construction and maintenance that may lead to infestation by wood destroying pests are summarizedin Fig. 26.
DAMAGE AND CORRECTION ACCORDING TO THE NATURE OF THE PEST
Once a thorough inspection has been completed and the structural pest control biologist is fully aware of the pest status and conditions likely to lead to pest infestations, decisions must be made to bring about effective control.
The basic control technique found to be most satisfactory for the control of subterranean termites is the provision of a chemical barrier between the soil (where the termite must return to obtain moisture) and the wood upon which they feed. This means preparing a small trench along all inner bearing walls and around pier posts. The trench needs tobe only 2 inches or 3 inches deep. Once prepared the trench is flooded with an approved, residual chemical (Fig. 27). Some companies also provide added protection by drilling all bearing timbers (mudsills, pier posts, girders) with 1/4 inch holes (which do not quite go all the way through) and pressure impregnating them with chemicals.
In treating the substructural areas in conventional construction (i.e., areas under a house with sufficient clearance to crawl under for inspection), the removal of all organic debris is necessary. Such debris would include everything of wood or paper that is lying on (or is in contact with), the soil.
In slab on grade construction, termites can work their way up through thesmallest of cracks in the floor. One application method that has come into use for treating this problem is drilling holes through concrete and masonry caps and walls and injecting of soil toxicant under pressure. Modern equipment has greatlyfacilitated this practice. When drill-treating is employed, always use a pressure-type slab injector and use as large a volume of material as possible. Soil types beneath the concrete or masonry caps should be considered, and the drilledholes spaced accordingly.
Structural correction includes the installation of mechanical barriers between wood and soil to eliminate the penetration of subterranean termites and moisture, as well as the removal and replacement of wood members structurally weakened by either termites, wood boring beetles, or fungus. Often this type of correction includes a combination of damage replacement and insulation.
Included in the barriers installation phases are the sealing-off of contacting earth-fills with concrete or masonry (Fig. 24), the installation of flash-walls, the plugging of hollow buttress walls and the pouring of concrete footings to insulate the bases of pillars, pilasters and stuccoed walls. This category also includes the raising of foundations, replacing wooden lower-steps with concrete and insulating embedded door-jambs, door casings and fence or gate posts which are fastened to structures. Concrete or masonry vent-wells, basal vent curbings, replacement of loosened exterior stucco and the drilling andplugging of vertical foundation cracks should also be included The second phase of structuralcorrection, which entails the removal and replacement of timbers weakened by theattack of wood destroying organisms, was at one time carried to extremes. In the case of subterranean termite attack, it is sometimespossible to reduce the magnitude of such an operation (after eliminating the source ofinfestation) by leaving the least damaged portion of the affected member in place and strengthening it by "scabbing on" a new and preferably treated member.
Due to its potential regrowth characteristic, fungus infection should be removed in its entirety wherever possible. After the source of moisture is eliminated, it may be feasible to reduce the volume of the repair to some extent and prevent reactivity by saturation of the new and adjacent timbering with an oil soluble wood preservative. If it should prove impractical to remove some of the slightly infected timbering due to structural barriers, it would be justifiable to saturate the affected member with preservative to strengthen it where needed. In correcting fungus damage, it is always advisable to use pressure-treated replacement timber if it can be obtained locally.
When replacing wood siding on an older frame house, it is often necessary to have an obsolete type of siding milled to match. Most lumber yards can reproduce any type you need, but in small quantities, the expense is considerable. In stucco repair, always attempt to have both texture and color properly matched.
Drywood termites present quite a different challenge. If the "kick holes" can be found and the infestation delimited, infestations can be individually drilled and chemically treated. If the infestation cannot be delimited (i.e., if there are many small infestations evident in many areas and it is reasonably certain that drywoods are in the studding and other inaccessible areas), fumigation is absolutely necessary. Few cases warrant the removal of inside or outside plaster or siding. Tent fumigation has become routine for a general infestation of drywood termites. In garages where most of the structural woods are exposed, it is a simple matter to drill into the infested wood at 8-inch intervals and dust toxicants into these holes. This dust is picked up by the termites and spread throughout the colony.
In the case of beetles that reinfest, the infested lumber must be removed and replaced, spot fumigated, or the entire structure fumigated. If true powderpost beetles are found in tool handles or artifacts of one kind or another, placing these materials in an oven at 250°F. until the center of the wood has reached that temperature willkill all stages of development.
When treating infestations of deathwatch beetles (which prefers our common structural wood, douglas fir) a moisture problem can be corrected, posts and other timbers can be removed and replaced, or the wood can be spot treated with chemicals. Generally, if a structural member is at least one-half destroyed, it should be removed.
Non-reinfesting beetles and horntails are simply allowed to escape. The holes made by the adults, as they work their way out of the wood have to be filled and properly refinished. If it is obvious that such adults, like longhorned beetles or metallic wood borers, are continuing to emerge as adults in ever increasingnumbers, spot treatment to prevent further unsightly holes may be necessary. It is sometimes very difficult to detect the presence of these organisms during their milling operation.
The most important move with carpenter ants is to locate the gallery. Once this is done, 1/4 inch holes can be drilled at the proper locations and the gallery impregnated with toxicants.
If carpenter bee holes are found in bridge timbers, posts, garage studding, or other timbers, a number of toxicants can be applied into the exposed holes and then resealed them. Rarely is it necessary to deal with these minor pests.
A KEY TO THE IDENTIFICATION OF DAMAGE CAUSED BY WOOD DESTROYING ORGANISMS
A biological key is a tool prepared by a specialist for students for determining names of specific or groups of organisms. The key should be prepared with terms understood by those likely to use it. Most of the members of the pest control industry are specialists their own right, therefore, the use of such terms as frass, pellet and tunnel are not unfamiliar and will be used in the following key.
Suppose someone has just handed you a piece of wood with some damage in it. There are no live specimens, but a functional key could help you determine the organisms which caused the damage.
1. No apparent galleries, chambers, tunnels, or excavations in the wood visible, and wood is or obviously has been wet (or moist) for months or more. 2
1'. Either galleries, chambers, tunnels, small holes, or excavations readily visible from the surface or within the wood 3
2. Checks at right angles and parallel to the grain of the wood Brown Cubical Rot
2'. Checks when present found running only parallel to grain of wood Other Wood Rots
3. Excavations containing pellets of distinct shape and/or size 4
3'. Excavations containing no pellets of any kind. 9
4. Pellets of distinct shape and size with longi- tudinal riflings 5
4'. Pellets varying in either size or shape and without riflings 6
5. Pellets no longer than the diameter of a paper clip wire, damaged wood apparently dry Western Drywood Termite
6. Cross-sectional view of tunneling distinctly round, pellets obviously varying in size and tapering at both ends 7
6'. Cross-sectional view of tunneling distinctly oval, pellets of similar size in groups or with masses of linear, fiberous shavings of wood 8
7. Tunnel indistinct due to the common presence of moisture and wood rotting fungi, an occasional distinctly shaped pellet most of which has been disintegrated to a fine powder Softwood Powderpost Beetle (Anobiidae)
7'.Tunnels very distinct running either with or against the wood grain, tunnels clean except for collections of distinctly shaped and sized pellets Deathwatch Beetles (Anobiidae)
8. Cross-sectional view of tunnel extremely fat, 4 or more times as wide as high Flat-headed Borers (Buprestidae)
8'. Cross-sectional view of tunnel no more than twice as wide as high Round-headed Borers (Cerambycidae)
9. Excavations or galleries obviously containing frass 10
9'. Excavation or galleries not containing frass; if frass is present, soil is also present 14
10. Individual particles of frass seen with the unaided eye or tunnels partially to wellcompacted with frass11
10'. Individual particles of frass as fine as chalk dust, individual tunnels less than 2 millimeters in diameter TruePowderspot Beetles (Lyctidae)
11. Damage found only on the surface of the wood justunder the bark 13
11'. Damage found within the wood 12
12. Tunnels uniform in size, less than 3 millimeters in diameter, damage normally found only in hardwoods Lead Cable Borer (Bostrichidae)
12'. Tunnels varying in size up to 3/8 of an inch in diameter, packed tightly with coarse frass having a sand paper-like texture Black Polycaon (Bostrichidae)
13. Tunnels or galleries radiating in all directions from a so-called egg gallery with visible egg nitches, individual tunnels not exceeding 4 millimeters in width Bark Beetles
13'. Tunnels progressing in a serpentine fashion over the surface of the wood, usually at least 4 times wider than deep Flat-headed Borers
14. Wood sparsely tunneled, diameter of the tunnels not exceeding 1 to 2 millimeters in diameter, tunnels stained dark brown to black Ambrosia Beetles
14'.Wood usually heavily tunneled or with large excavations, if sparsely tunneled the diameter of the tunnel is from 1/2 to 3/4 of an inch (13 to 20 millimeters) 15
15. Wood found in association with or within brackish or salt water 16
15'. Wood not found in association with or within brackish or salt water 17
16. Tunnels one to many, large (from 3/8 to 1 inch in diameter) (10 to 25 millimeters), tubular, nearly perfectly, circular holes as seen in cross-section, tunnels lined with white, smooth shell Pileworms (related to clams, oysters)
16' Tunnels multiple, extremely small, both inside and on the surface of the wood, tunnels never lined with shells Limnoria (Crustacean)
17. Tunnels one to many, nearly perfectly circular in cross-section, extending with the grain of the woodin either direction from an entrance hole, 1/2 to 3/4 (13 to 20 millimeters) of an inch in diameter (Carpenter Bees)
17'. Tunnels forming excavations of indefinite shape or size 18
18. Excavations containing masses of soil particles, surfaces of galleries frequently speckled by liquid feces, obvious avoidance of hard, summer wood SubterraneanTermites
18'. Excavations immaculate, little indication that the hard, summer wood has been avoided (similar to that of drywood termites and frequently talces over such a gallery Carpenter Ants
- Anonymous. 1946. Preventing Damage to Buildings by Subterranean Termites and Their Control. USDA Farmers' Bul. No. 1911.
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- Beal, Raymond H. 1967. Formosan Invader. Pest Control (February).
- Beal, R.H. and L. S. Stauffer. 1967. How Serious the Formosan Termite Invasion? Forests and People Magazine (Third Quar. Issue).
- Bess, Henry A. 1970. Termites of Hawaii and the Oceanic Islands. Termites. Vol. 2(449-476). Academk Press, Inc.
- Be, Henry A. 1971. Control of the Drywood Termite, Cryptotermes brevis, in Hawaii. Hawaii Agri. Exp. Stat. Tech. Bul. No. 87.
- Borror, Donald J. and Dwight M. DeLong. 1971. An Introduction to the Study of Insects (Third Edition). Holt, Rinehard and Winston.
- Eames, Arthur J. and Laurence H. MacDaniels. 1947. An Introduction to Plant Anatomy. McGraw-Hill Book Company.
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- Chamberlain, W. J. 1949. Insects Affecting Forest Products and Other Materials. OSC Cooperative Association. Corvallis, Oregon.
- Doan. R. W., E. C. Van Dyke, W. J. Chamberlain, and H. E. Burke. 1936. Forest Insects. McGraw Hill Book Company.
- Ebeling. Walter.and Roy J. Pence. 1958. Termite Control. Prevention and Control of the Western Subterranean Termite. California Agri. Exp. Sta. Cir. 469.
- Ebeling, Walter. 1968. Termites, Identification, Biology, and Control of Termites Attacking Buildings. Calif. Agri. Exp. Sta. Manual 38.
- Fisher, W. S. 1950. A Revision of the North American Species of Beetles Belonging to the Family Bostrichidae. USDA Misc. Pub. 698.
- Gerberg, E. J. 1957. The New World Species of Powder-Post Beetles Belonging to the Family Lyctidae. USDA Tech. Buf. No. 1157.
- Hetrick, L. A. 1954. Termites and Other Wood Infesting Insects. Florida Agri. Exp. Sta. Bul. 157.
- Hunt, Ronald W., Sr. 1966. Inspection for Wood Destroying Organisms (As Practiced in Western USA) Published by Pest Control Operators of California, Inc.
- Johnston, H. R. and R. H. Beal. 1969. What's New with the Formosan Termite. Pest Control. Vol. 7(2):24, 26, 30, 32..
- Johnston, H. R., Virgil K. Smith, and Raymond
- H. Beal. 1972. Subterranean Termites, Their Prevention and Control in Buildings. USDA Bul. No. 64 (Revised).
- Lyon, . Robert L. 1958. California Flatheaded Borer. USDA Forest Pest Leaflet 24.
- Pickens, A. L. 1934. The Biology and Economic Significance of the Western Subterranean Termite, Reticulitermes hesperus.In "Termites and Termite Control" (C.A. Kofoid, ed., reprinted and partially revised, 1965), pp 157-186. Berkeley: Univ. Calif. Press.
- St. George, R. A., H. R. Johnston, and R. J. Kowal. 1960. Subterranean Termites, Their Prevention and Control in Buildings. USDA Home and Garden Bul. 64.
- Smith, V. K., Jr. and H. R. Jonston. 1962. East ern Subterranean Termite. USDA Forest Pest Leaflet 68.
- Smythe, Richard V. and Fairie L. Carter. 1970. Feeding Responses to Sound Wood by Coptotermes formosanus, Reticulitennes flavipes, and R. viginicus (Isoptera:Rhinoterrnitidae). Ann. Ent. Soc. Amer. Vol. 63(3):841-850.
- Snyder, Thomas E. 1958. Control of Non Subterranean Termites. USDA Farmers' Bui. No. 2018.
- Sutherland, Douglas W. S., Willard G. Harwood, and James L. Skaptason. 1973. EAP List of Insects and Other Organisms. Office of Pesticides Programs. U.S. Environmental Protection Agency.
- Verrall, Arthur F.1966.Building Decay Associated with Rain Seepage. USDA Tech. Bui. 1356.
- Weesner, F. M.1965. The Termites of the United States. National Pest Control Association. Elizabeth, New Jersey.
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